1 files changed, 78 insertions, 0 deletions
diff --git a/packages/asset-buyer/src/order_providers/standard_relayer_api_order_provider.ts b/packages/asset-buyer/src/order_providers/standard_relayer_api_order_provider.ts
new file mode 100644
index 000000000..be3e9da50
--- /dev/null
+++ b/packages/asset-buyer/src/order_providers/standard_relayer_api_order_provider.ts
@@ -0,0 +1,78 @@
+import { APIOrder, HttpClient, OrderbookResponse } from '@0xproject/connect';
+import * as _ from 'lodash';
+
+import {
+    AssetBuyerError,
+    OrderProvider,
+    OrderProviderRequest,
+    OrderProviderResponse,
+    SignedOrderWithRemainingFillableMakerAssetAmount,
+} from '../types';
+import { assert } from '../utils/assert';
+import { orderUtils } from '../utils/order_utils';
+
+export class StandardRelayerAPIOrderProvider implements OrderProvider {
+    public readonly apiUrl: string;
+    private readonly _sraClient: HttpClient;
+    /**
+     * Given an array of APIOrder objects from a standard relayer api, return an array
+     * of SignedOrderWithRemainingFillableMakerAssetAmounts
+     */
+    private static _getSignedOrderWithRemainingFillableMakerAssetAmountFromApi(
+        apiOrders: APIOrder[],
+    ): SignedOrderWithRemainingFillableMakerAssetAmount[] {
+        const result = _.map(apiOrders, apiOrder => {
+            const { order, metaData } = apiOrder;
+            // calculate remainingFillableMakerAssetAmount from api metadata, else assume order is completely fillable
+            const remainingFillableTakerAssetAmount = _.get(
+                metaData,
+                'remainingTakerAssetAmount',
+                order.takerAssetAmount,
+            );
+            const remainingFillableMakerAssetAmount = orderUtils.calculateRemainingMakerAssetAmount(
+                order,
+                remainingFillableTakerAssetAmount,
+            );
+            const newOrder = {
+                ...order,
+                remainingFillableMakerAssetAmount,
+            };
+            return newOrder;
+        });
+        return result;
+    }
+    /**
+     * Instantiates a new StandardRelayerAPIOrderProvider instance
+     * @param   apiUrl  The standard relayer API base HTTP url you would like to source orders from.
+     * @return  An instance of StandardRelayerAPIOrderProvider
+     */
+    constructor(apiUrl: string) {
+        assert.isWebUri('apiUrl', apiUrl);
+        this.apiUrl = apiUrl;
+        this._sraClient = new HttpClient(apiUrl);
+    }
+    /**
+     * Given an object that conforms to OrderProviderRequest, return the corresponding OrderProviderResponse that satisfies the request.
+     * @param   orderProviderRequest   An instance of OrderProviderRequest. See type for more information.
+     * @return  An instance of OrderProviderResponse. See type for more information.
+     */
+    public async getOrdersAsync(orderProviderRequest: OrderProviderRequest): Promise<OrderProviderResponse> {
+        assert.isValidOrderProviderRequest('orderProviderRequest', orderProviderRequest);
+        const { makerAssetData, takerAssetData, networkId } = orderProviderRequest;
+        const orderbookRequest = { baseAssetData: makerAssetData, quoteAssetData: takerAssetData };
+        const requestOpts = { networkId };
+        let orderbook: OrderbookResponse;
+        try {
+            orderbook = await this._sraClient.getOrderbookAsync(orderbookRequest, requestOpts);
+        } catch (err) {
+            throw new Error(AssetBuyerError.StandardRelayerApiError);
+        }
+        const apiOrders = orderbook.asks.records;
+        const orders = StandardRelayerAPIOrderProvider._getSignedOrderWithRemainingFillableMakerAssetAmountFromApi(
+            apiOrders,
+        );
+        return {
+            orders,
+        };
+    }
+}